In many power applications, semiconductors are used in the form of so-called power semiconductor modules which contain one or more semiconductor components or, if appropriate, additional components. Depending on the purpose of application, the individual modules have different packaging. However, irrespective of the type of packaging, it is necessary in every case to connect the semiconductor components and, if appropriate, further components to one another electrically. Furthermore, the components are intended for connection to external connecting elements. The technology for connecting between the individual components represents a significant problem here.
Frequently applied connecting technology in this context is so-called wire bonding. In this context, wires made of aluminum are attached to a contact face made of aluminum or copper by means of ultrasonic energy, an intermetallic connection being produced. In addition, by way of example, ThinPak, MPIPPS or flip-chip technologies are also used to a greater or lesser extent. All these connection techniques have their specific advantages and disadvantages, with the disadvantages predominating in most application cases.
Disadvantages of the most frequently used connection technology, wire bonding, are, for example, the very slow, very costly and thus cost-intensive process per se as well as the high susceptibility to faults both during manufacture and during operation of the module itself. What is certainly the greatest disadvantage of wire bonding is here the fact that in particular semiconductor components are subjected to large mechanical stresses during the bonding process, and these lead to a high rejection rate. Furthermore, wire bonds can also easily break during the subsequent manufacturing steps or during operation of the semiconductor module, which in turn increases the rejection rate and reduces the reliability of the semiconductor module.
In order to avoid these disadvantages, so-called wire bondless modules, which are frequently based on the application of lamination techniques, have frequently been used in recent times. An example of such a module and its manufacturing method are described, for example, in DE 196 17 055 C1.
Such a power semiconductor module comprises at least one electrically insulating substrate on which surfaces made of an electrically conductive material are patterned. Semiconductor components are electrically connected to these surfaces, the surfaces and/or semiconductor components being additionally connected to connecting elements which lead to the outside. The semiconductor components are electrically connected to the patterned surfaces here on one side by soldering or by means of pressure contact and are in contact on the other side with a flexible printed circuit board by soldering or by means of pressure contact. The arrangement is insulated by means of lamination using patterned insulation intermediate layers, cutouts being provided for the semiconductor components in order to make contact. These cutouts can already be provided in advance, in which case very good fitting accuracy has to be achieved. Another method is to laminate an insulating intermediate layer without cutouts and to remove the insulation at the locations provided for that purpose, for example by means of mechanical processing or preferably by means of lasers. Although significantly higher precision is achieved here there is then the risk either of parts remaining on the underlying surface, which make the formation of contacts more difficult or even prevent it entirely, or else of material which lies under the intermediate layer, that is to say a contacting face or a component, being damaged. Consequently, precise erosion is relatively time consuming.